Central Nervous System Part III

Question 1

Define/differentiate concussion, contusion, subdural/subarachnoid hematoma, and cerebral edema.

Answer 1

Concussion: temporary alteration in brain function – typically following a blow to the head; repeated concussions can cause cumulative damage

Contusion: permanent damage caused by bruising of the brain

Subdural or Subarachnoid Hemorrhages: ruptured blood vessels bleed into these available spaces; pressure from the blood may compress the brain and cause sudden, neurological decline

Cerebral Edema: swelling of brain associated with traumatic head injury

Question 2

What is ischemia? What is a cerebral vascular accident (CVA)? How do most CVAs occur?

Answer 2

Ischemia: any tissue deprived of blood supply - can lead to tissue death

Ischemia of brain tissue can be caused by blockage of a cerebral artery by a blood clot

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Question 3

Define hemiplegia. How do CVAs cause hemiplegia?

Answer 3

Hemiplegia - paralysis on one side of the body often caused by CVA – sensory and speech deficits may also occur

Question 4

What is a TIA? What is TPA?

Answer 4

Transient Ischemia Attacks (TIA): temporary episodes of reversible cerebral ischemia; often a warning sign of a larger CVA

Tissue Plasminogen Activator (TPA) is the most effective treatment for acute stroke

Question 5

Define Alzheimer’s Disease. What are some symptoms? What are 2 potential anatomical structures associated with Alzheimer’s Disease that cause neuronal death?

Answer 5

Alzheimer’s Disease (AD) - Progressive, degenerative disease of the brain that results in dementia

Symptoms - memory loss, short attention span, disorientation, eventual language loss, irritability, moodiness, confusion, and hallucinations

Neurofibrillary Tangles: formed from the protein tau inside the neurons; tangles interfere with the neuron’s transport mechanisms and eventually kill the neurons

The brain shrinks as neurons die

Question 6

Define Parkinson Disease. What are some symptoms? What is a potential cause? What is a treatment?

Answer 6

Parkinson’s Disease - Degeneration of dopamine-releasing neurons of the substantia nigra

The basal nuclei deprived of dopamine become overactive – results in tremors

Overall cause is unknown, but theories exist about mitochondrial abnormalities or protein degradation pathways

Treatment: L-dopa (a dopamine precursor), deep brain stimulation, and gene therapy

Question 7

Define Huntington Disease. What causes it? What are some symptoms? What is a potential treatment?

Answer 7

Huntington’s Disease

Fatal hereditary disorder caused by the accumulation of the protein huntingtin in brain cells – leads to degeneration of basal nuclei and the cerebral cortex

Onset is often in middle age
Initial symptoms: wild, jerky, “flapping”-like movements; followed by mental deterioration

“Chorea”: excessive, writhing movements; Greek for “dance”

Condition is typically fatal within 15 years

Treatment: drugs that block the effects of dopamine – stem cell implant research is promising

Question 8

Where does the spinal cord begin? Where does it end?

Answer 8

The spinal cord begins at the foramen magnum and ends at the L1/L2 vertebra

Question 9

What 2 functions does the spinal cord provide?

Answer 9

Provides 2-way communication between the brain and body

Acts as a major reflex center – reflexes are initiated and completed at the spinal cord

Question 10

How is the spinal cord protected?

Answer 10

The spinal cord is protected by bone, meninges, and CSF

Question 11

What can you find in the epidural space? What is the clinical importance of the epidural space?

Answer 11

Epidural Space - cushion of fat and a network of veins in the space between vertebrae and the spinal dura mater

Question 12

What can you find in the subarachnoid space?

Answer 12

Subarachnoid Space - space between the arachnoid and pia maters; it is filled with CSF

Question 13

Define and be ready to identify: conus medullaris, filum terminale, denticulate ligaments, cauda equina, ventral median fissure, dorsal median sulcus, and central canal.

Answer 13

The spinal cord terminates in a cone-shaped structure called the conus medullaris

Filum Terminale: a fibrous extension of the conus medullaris covered with pia mater. It extends to the coccyx and anchors the spinal cord.

Denticulate Ligaments: extensions of pia mater that secure the spinal cord to the dura mater

Cauda Equina: collection of nerve roots at the inferior end of the vertebral canal

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Question 14

Why are there cervical and lumbar enlargements in the spinal cord?

Answer 14

Cervical and Lumbar Enlargements - areas of the spinal cord where the nerves servicing the upper and lower limbs arise

Question 15

Draw out how spinal nerves exist the spinal cord at each vertebral level.

Question 16

The spinal cord’s central canal is filled with CSF, and it is continuous with the _______________.

Answer 16

brain’s 4th ventricle

Question 17

What are the 3 gray columns of the spinal cord? What is located in each column?

Answer 17

Dorsal Horns: interneurons that receive somatic and visceral sensory inputs

Ventral Horns: some interneurons, mostly somatic motor neurons

Lateral Horns: only exist in thoracic and superior lumbar regions; autonomic (sympathetic) neurons that innervate the visceral organs

Question 18

What is the gray commissure?

Answer 18

Gray Commissure: bridge of gray matter that connects the masses of gray matter on either side of the central canal

Question 19

Define, know the function of, and be ready to identify: ventral root, dorsal root, and spinal nerve.

Answer 19

Ventral Roots: bundle of motor neuron axons that exit the ventral spinal cord

Dorsal Roots: sensory inputs into the dorsal spinal cord

Dorsal Root (Spinal) Ganglion: cell bodies of the sensory neurons

Spinal Nerves: formed by the fusion of the dorsal and ventral roots

Question 20

Draw out how the spinal cord’s gray matter is divided into 4 groups.

Question 21

What are the 3 white funiculi of the spinal cord? What makes white matter white?

Answer 21

Dorsal (Posterior)
Lateral
Ventral (Anterior)

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Question 22

What type of communication is happening with each direction of white fiber tract?

Answer 22

Ascending: up to the higher centers (sensory inputs)

Descending: from the brain to the spinal cord or to the lower cord levels (motor outputs)

Transverse: from 1 side of the spinal cord to the other (commissural fibers)

Question 23

The spinal cord is particularly sensitive to _____________________.

Answer 23

Direct pressure

Question 24

Define paresthesia and paralysis. What are the 2 types of paralysis?

Answer 24

Paresthesia: loss of sensory function; caused by damage to the dorsal roots or sensory tracts

Paralysis: loss of motor function; caused by damage to the ventral roots or ventral horn cells

2 Types: Flaccid or Spastic

Flaccid Paralysis: severe damage to the ventral root or ventral horn cells

• Impulses do not reach the skeletal muscles
• There is no voluntary or involuntary control of the muscles
• Muscles atrophy secondary to disuse

Spastic Paralysis: damage to the upper motor neurons of the primary motor cortex or their axons in the spinal cord

• Spinal more neurons remain intact; muscles are stimulated by reflexes
• There is no voluntary control of muscles, only relfex
• Muscles often shorten permanently (muscle contracture)

Question 25

Be ready to explain how each type of paralysis occurs and how you would expect it to look in a patient.

Answer 25

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Question 26

Differentiate paraplegia and quadriplegia. Know (generally) what spinal cord level injuries are likely to result in these conditions.

Answer 26

Paraplegia: transection of the spinal cord between T1 and L1

Quadriplegia: transection of the spinal cord in the cervical region

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Question 27

What is poliomyelitis? What causes it? What portion of the spinal cord is harmed? What are the short and long term symptoms?

Answer 27

Poliomyelitis

An epidemic in the late 1940s and 1950s – vaccine invented in 1952

Destruction of the ventral horn motor neurons by poliovirus

Symptoms: fever, headache, muscle pain and weakness, and loss of certain somatic reflexes

Muscles atrophy because of paralysis

Death can occur from paralysis of respiratory muscles or cardiac arrest

As a result of progressive neuron loss, survivors often develop postpolio syndrome years later

Question 28

What is ALS? What might cause it? What portion of the spinal cord is harmed? What is a potential treatment?

Answer 28

Amyotrophic Lateral Sclerosis (ALS)

Also called “Lou Gehrig’s Disease”

Destruction of ventral horn motor neurons and the fibers of the pyramidal tracts

Symptoms: loss of abilities to speak, swallow, and breathe

Death typically occurs within 5 years

Caused by the interaction of environmental factors and genetic mutations involving RNA processing

Treatment: only treatment is a drug that interferes with glutamate signaling called riluzole – glutamate is a neurotransmitter indicated as a potential cause of neuron death in a couple different conditions